Its pretty simple. Whenever you spend a benny on anything, roll a d6; on a 5 or a 6, for the next three rounds, you add a d6 to any trait roll you make. That Rage Die, as I call it, can also Ace, like any other Trait Die.

Its meant to represent the hero drawing on their will and convictions to succeed at things, and I think it does a pretty good job of it. There's also an edge that goes with it, Conviction, that lets you, once per session I think, activate Righteous Rage automatically.